As is known in the art, certain abnormalities in organs, such as tumors and aneurysms are manifested as a protrusion from the organ. For example, an intracranial aneurysm is a bulge or dilation in one of the arteries supplying the brain with blood. It bears the medical risk of vessel rupture leading to intracranial bleeding, which in some cases can cause irreparable neurological damage or death of the patient. Aneurysms may be classified according to their shape into saccular and fusiform aneurysm. A saccular aneurysm resembles a small bubble that appears off the side of a blood vessel. A fusiform aneurysm is a bulging around the entire circumference of the vessel. Aneurysm may also be classified according to their site in the circulation into sidewall and bifurcation aneurysms.
As is also known in the art, two approaches exist for the treatment of brain aneurysms. The endovascular approach is performed under guidance from X-ray angiography images. It involves the insertion of wire coils or glue inside the aneurysm with the intention of forming a blood clot inside in order to relieve the pressure against the aneurysm's wall. The second approach for treatment of aneurysms involves neurosurgical clipping of the aneurysm at its neck.
Some aneurysms rupture quickly after their formation, while others may remain without complications for many years.
Findings of the International Study on Unruptured Intracranial Aneurysms (ISUIA) imply an estimated risk of aneurysm rupture between 0.5% and 2.5% per year. The risks and complications associated with either form of treatment combined with the uncertainty of aneurysm rupture imply the need for an approach to differentiate aneurysms that carry a high risk of rupture from those of low risk.
Recent studies suggest numerous factors affecting the risk of aneurysm rupture including demographic and genetic factors, patient history, size and dimensions of the aneurysm, blood flow dynamics, geometry of the parent artery, and the shape of the aneurysm. Investigations that have focused on aneurysm shape and surface attached characteristics across a number of subjects have generally considered global aspects of aneurysms, such as dome height and maximum dimension. Similarly computational fluid dynamics (CFD) studies of aneurysm formation, growth, and risk of rupture compare overall simulation aspects or global (on the whole aneurysm surface) statistics of the simulation results. While some of these investigations were group cross-sectional and longitudinal studies, these studies did not address quantitative comparison of local aneurysm characteristics.
More particularly, studies have revealed some overall shape characteristics that affect the risk of rupture, including aneurysm size, shape, and aspect ratio. Other recent studies have implied a link between the overall distribution of hemodynamic variables such as wall shear stress (WSS) and the risk of rupture. However, since populations of ruptured and unruptured aneurysms overlap under many of the metrics designed to assess the risk of rupture, it is still not possible to estimate the risk of rupture of some aneurysms with reasonable certainty. Large longitudinal and cross-sectional group studies that could reveal possible links between the risk of rupture and the distribution of local variables, such as WSS, are currently not possible due to the absence of an approach for establishing correspondence across aneurysms in different patients and in the same patient at different points in time. The availability of such a technique will enable the use of analysis methods that could unravel important local factors affecting aneurysm rupture.
Currently, there exists no approach to compare local aneurysm surface, or surface attached characteristics (such as those derived from CFD simulations) across a number of different individuals or the same individual at different time points.
Thus, as noted above, it would be advantageous if one could distinguish aneurysms that rupture quickly after their formation from aneurysms that may remain without complications for many years.